A billfold is a small folding wallet that holds paper money, typically made of leather or fabric. The name comes from its original purpose: folding bills in half to keep them neat and protected.

When you open a billfold, you'll usually find compartments for cash, slots for credit cards or ID, and sometimes a clear window for a driver's license or photo. People have traditionally carried billfolds in pockets or kept them in purses or bags.

Today, many people just say “wallet” instead, though the two words mean essentially the same thing. Your grandfather might still call his wallet a billfold, and you might hear the term in older books or movies. Some people also use billfold specifically to describe the slim, fold-over style of wallet, as opposed to bulkier styles with zippers or snaps.